Question

A and B do a piece of work in 12 days, B and C in 15 days and A and C in 20
days. In how many days A, B and C together will complete the work.?
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Answer 1

Answer:

a+ b = 12

b+c = 15

c+ a= 20

LCM of 12,15,20 is 60

(a+ b+b+c+ c+ a)=((60÷12)+(60÷15)+(60÷20))

2(a+b+c)= (5+4+3)

(a+b+c)=((12÷2))

a+b+c = 6

a = 2

b = 3

c = 1

final of A,B,C working together is

60÷(a+b+c)

60 ÷ 6 = 10